WHAT'S UP DOC? Tetanus

Tuesday

Apr 25, 2017 at 4:22 PMMay 3, 2017 at 12:04 PM

By Dr. Jeff Hersh / Daily News Correspondent

Q: I thought there was no tetanus anymore in the United States, so why do I need a tetanus shot?

A: Tetanus is not passed from person to person. It is caused by a neurotoxin produced by the bacterium Clostridium tetani, which lives in the gut of many animals and so can exist in soil/dust pretty much anywhere. Therefore, it is not a disease that can be eradicated. Tetanus is one of the diseases that does not give lifelong immunity.

Typically C. tetani spores enter the body through a contaminated wound. Since C. tetani is an obligate anaerobe, the spores can only transform into bacteria in oxygen-poor environments. This happens in dead or damaged body tissue (which is poorly oxygenated), typically the tissue damaged from the trauma that created the wound. Once the bacteria begin to grow they produce neurotoxin (tetanospasmin, also known as tetanus toxin). The toxin gets into the blood and then into the nerve cells in the brain and/or spinal cord. Once in the nerves it binds, tightly and permanently, to a neurotransmitter where it blocks the ‘off’ signal, effectively locking the nerve into the ‘on’ position.

After exposure it takes two days to three weeks (average 7 to 10 days) for the patient to develop symptoms. The symptoms are due to the continuously excited nerve impulses that cause various muscles to be in constant spasm. The lockjaw of tetanus (another term for this condition) is due to over-stimulation of the chewing muscles and is the most common symptom, manifesting in 50 to 75 percent of patients.

Generalized tetanus is by far the most common type (over 80 percent of cases); local, cephalic and neonatal tetanus are the other types. In addition to lockjaw, symptoms of generalized tetanus include fever, diarrhea, sweating, irritability, fast heartbeat, muscle spasms/contractions (which can even break bones or cause tendon damage), rigid abdomen, swallowing problems, and/or others.

Local tetanus presents with muscle contractions and/or spasms limited to one arm, leg or body part. Cephalic tetanus, usually due to a wound in the head or neck, presents with problems with one or more of the cranial nerves, and may even be confused with a stroke. Finally, neonatal tetanus presents in newborns with poor feeding, difficulty opening their mouth, clenched hands and/or feet, and/or overall increased muscle tone.

The reason tetanus is so uncommon in the United States is because of almost universal vaccination to prevent it. The tetanus toxoid vaccination was introduced in the 1940’s. Since then cases of tetanus have dropped precipitously. There are now only about 10 to 30 cases in the United States per year, and these are almost always in people who are not current on their tetanus vaccination.

In developing nations, where tetanus vaccination is not as common, the rate of this disease is much higher. Worldwide there are still about a million cases of tetanus, with up to half a million deaths, per year.

The main risk factor for developing tetanus is not having an up to date vaccination. Any contaminated wound (including puncture wounds) may become problematic since the C. tetani spores exist almost everywhere.

Tetanus in the United States is more common in the elderly, mostly because the immune system weakens with age and because many do not keep up with their vaccinations. Neonates born to a mom who is not up to date on her tetanus vaccination, and who then have their umbilical cord remnant contaminated, are at risk.

The diagnosis of tetanus is based on the symptoms and physical exam; over 90 percent of patients recall a wound that may have been the cause. Other causes of the patient’s symptoms must be considered.

Since the toxin binding is strong and permanent, the focus of treatment is minimizing further toxin production, controlling symptoms and giving supportive care until the neurotransmitters in the affected nerves regenerate. Appropriate antibiotics and wound management can kill the bacteria to minimize further toxin production, and tetanus immune globulin can help neutralize toxin which has not yet bound to neurotransmitters. Control of muscle spasms and supportive care (for example supporting nutrition, breathing, etc.) in an Intensive Care Unit setting are indicated. Despite this care, up to 10 to 15 percent of patients die; the mortality rate is much higher in developing nations and in neonatal cases.

Prevention of tetanus is crucial. This should begin with appropriate childhood DTaP (diphtheria, tetanus, and pertussis) vaccinations at ages 2, 4 and 6 months, then again at 15 to 18 months and a booster between ages 4 and 6. After this complete initial childhood series, everyone should have a booster every 10 years.